We plan to continue to study the mechanisms for augmented synthesis of cholesteryl ester in atherosclerotic microsomes. In this connection, we intend to investigate the possibility that a higher concentration of acyl-CoA in atherosclerotic microsomes as compared to normal microsomes may be responsible for augmented cholesteryl ester synthesis. We plan to test indirectly the possibility that augmented cholesteryl ester synthesis is due to a higher concentration of enzyme by measuring cholesterol-esterifying activity of normal and atherosclerotic microsomes at substrate concentrations of acyl-CoA and cholesterol sufficient to saturate the enzyme. We plan to continue our efforts to solubilize and purify the cholesterol-esterifying enzyme (acyl-CoA: cholesterol acyltransferase), first from liver and later from arterial tissue. We plan to study uptake and utilization of fatty acid by normal and atherosclerotic aortas at varying molar ratios of FFA-albumin. BIBLIOGRAPHIC REFERENCES: Hashimoto, S. and Dayton, S.: Influence of Microsomal Cholesterol Concentratations on the Cholesterol Esterifying Activity of Normal and Atherosclerotic Aortas. Artery, 4:308-318, 1975.